JPS6124706A - Wind resistant vibration-proof apparatus structure - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of Application of the Invention] The present invention relates to a windproof and vibration isolating device for long angular structures such as main towers and girders of suspension bridges and cable-stayed bridges.

[Technical background of the invention]

Long structures such as main towers and girders of suspension bridges and cable-stayed bridges have low rigidity and tend to be easily affected by wind action. Furthermore, since these structures are generally corner-shaped structures, they suffer from dynamic effects of wind such as vortex-excited vibrations caused by Karman vortices generated from corners and gear lopping caused by separation of airflow from corners. Often.

Measures to deal with these dynamic effects of wind include (α) increasing the rigidity of the structure, (b) increasing the damping performance of the structure, and (C) making the shape of the structure aerodynamically favorable.

The method of increasing the rigidity of the structure (α) is to increase the wind speed at which vortex-excited vibrations and gear lopping occur, but if we focus too much on rigidity alone, the steel weight will increase, resulting in an uneconomical result. There is also.

The method (h) to improve damping performance is effective in damping dynamic effects of wind such as vortex-excited vibrations and gear pitching. Problems remain in terms of performance and maintenance.

As a means of achieving an aerodynamically favorable shape in (C), proposals include making the cross section of the structure streamlined, installing gratings (air vents), installing flow guide plates, and installing a center barrier. has been done.

In particular, the method of attaching flow guide plates to the corners of the structure's cross section has the advantage that it does not depend on changing the basic surface of the structure and does not cause cross-sectional defects like grating, and is a promising wind resistance measure. It is attracting attention as

A flow guide plate aimed at isolating the dynamic effects of wind such as vortex excitation vibration and gear roping in a square structure has already been published in Publication of Utility Model Publication No. 3-17071. T-! Several proposals have been made, as seen in 3Koza No. 3 Publication, but these do not necessarily work effectively, as will be described later, and are not particularly effective against the occurrence of gear lopping. For gearropping, the above (Z)
The measures to increase the rigidity of the structure described in section 2.2 are also used.

As an example of a angular structure, when assuming a cross section like the IT diagram, in such a cross section, when the period of the Karman vortex generated from the corner and the natural frequency of the structure match, the structure There is a problem in that objects resonate in a direction perpendicular to the direction of the wind, more specifically, vortex excitation vibration occurs, and when the wind speed further increases, gear lopping occurs due to separation of airflow from corners. This will be explained using the results of wind tunnel experiments for structures. The spear diagram shows the wind resistance response of a square structure without a flow guide plate as shown in Figure 1, that is, the V-A curve, which shows the relationship between the dimensionless amplitude A/D and the converted wind speed V/N17D. It shows. Here, the wind speed I NW is the bending frequency, D
is the apparent width of the structure, and A is the amplitude of the structure.

As is clear from Figure 7, the converted wind speed V/Ni11D=
In 4-9, a large-amplitude vortex excitation vibration such as dimensionless amplitude A/D
Gear ropping occurs in the region of 13, and the response amplitude becomes A/D>Ol, exhibiting aerodynamically unstable behavior.

The yakko diagram is a structure in which a flat flow guide plate is installed at the corner of a plane parallel to one direction of the wind indicated by the arrow, with a required gap, and the corresponding V-A curve is The spear is shown in the diagram. As shown in the figure, this structure generates a large-amplitude vortex-excited vibration with a dimensionless amplitude A/D>(12/?) around D=7 at the converted wind speed V/N, and the converted wind speed V/H In the area where MaD≧33,
Due to gearropping, the response amplitude is A/D>Ol7, and although the wind speed range where vibrations occur in the structure shown in the figure without a flow guide plate has been reduced, it is still insufficient as a wind-resistant and vibration-proof device. It is.

In order to solve such problems, conventionally, as mentioned above, Japanese Utility Model Publication No. J-707/, Publication of Utility Model A;
-1) As can be seen in Publication No. 3, at the corner of the angular structure shown in Figure 3, there is a structure that is parallel to one surface parallel to the wind direction and expands outward relative to the other two surfaces. It has been proposed that a flow guide plate having a bent cross-sectional shape, that is, a rectangular cross-sectional shape, is disposed. Figure 9 is the V-A curve of the structure shown in Figure 3, and as is clear from the figure, the vortex-excited vibrations seen in Figure 1 and t' have disappeared. but,
Gear ropping occurs in the range of converted wind speed V/NηD≧2, and large-amplitude vibrations with dimensionless amplitude A/D)O/R occur, which is insufficient as a wind-resistant and vibration-proof device.

[Purpose of the invention]

The present invention has been made in view of the above circumstances, and it solves the problems of the prior art by simple and rational means, and makes it possible to use square structures such as main towers and girders of suspension bridges and cable-stayed bridges. It is an object of the present invention to provide a wind-proof and vibration-proof device which can rationally prevent not only the occurrence of vortex-excited vibration but also the gallop phenomenon, and which is economically effective.

[Structure of the invention]

In order to achieve the above object, the present invention configures the main towers and girders of a suspension bridge or cable-stayed bridge with a square structure, and provides a required ventilation passage gap in the longitudinal direction of the corner of the square structure. A flow guide plate having an arcuate cross section is separately disposed through the flow guide plates to prevent vortex excitation and gear ropping.

[Explanation of Examples]

The present invention will be described in detail with reference to the yoke +, j-, /;, /θ diagrams. Figure Q is a front view of the diagonal stay, Figure S is a cross-sectional view of the main tower, which is a square structure, and Figure 6 is a fang! It is a reference diagram shown for explaining the figure. (1) in the figure q is the main tower,
(2) is the bridge girder, and (3) is the cable-stayed cable.

(4) is the pier. The windproof and anti-vibration device shown in the yPS diagram will be explained. Flow guide plates (5) having an arc-shaped cross section are attached to all corners of the main tower (1) with predetermined gaps therebetween. One of the tangential directions of the arcuate end of the flow guide plate (5) is parallel to the plane (lα) in the airflow direction indicated by the arrow, and the tangential direction of the other arcuate end is parallel to the plane (lα) in the airflow direction. )
The cross section is facing inward. The center point 01 of the circle with respect to the arc is not located at a symmetrical position with respect to the plane in the airflow direction (lα) and the plane in the perpendicular direction to the airflow (/b), as shown in Fig. 6, but in Fig. 2z. As shown, it is arranged slightly eccentrically toward the plane perpendicular to the airflow (/h), so that the air passage between the flow guide plate (5) and the main tower (1) sharply decreases at the corner of the cross section. Try to avoid. In addition, by eccentrically centering the center point 08 of the circle, the arc-shaped flow guide plate (5) can fully extend to the inside of the cross section of the main tower.
The tangential direction of the arc end is not perpendicular to the plane of the airflow direction (lα) as shown in Fig. 6, but is θ as shown in the figure.
<Consideration should be made so that the current guide plate (5) forms a tag (acute angle) and easily guides the wind.

The io diagram is a wind resistance diagram (v-A curve) when the flow guide plate according to the present invention as shown in fig. 3 is applied. As is clear from Fig. 10, the occurrence of vortex-excited vibration and gearropping, which are observed in the case of the conventional flow guide plate mentioned above, is not observed at all in the entire range of converted wind speed O-SO, and the aerodynamic It shows stable properties. In addition, the spear lo diagram is the angle of attack α−
Although this is a response diagram for the case of angle of attack α=f, it has been confirmed by wind tunnel experiments that it is aerodynamically stable at each angle of attack of i and cog.

〔Effect of the invention〕

As described above, according to the present invention, the vibration isolating effect is far greater than that of conventional wind-resistant and vibration-proof devices, and since the cross-sectional shape of the flow guide plate is arcuate, the wind direction (angle of attack or This is an excellent wind-resistant and vibration-proof device that can effectively exhibit vibration-proofing effects over a wide range of angles.

Furthermore, since the shape is a part of a circle (circular arc), it is easy to manufacture and manage construction, and the flow guide plate of the present invention is suitable for economical trends. It is desirable to attach it to the above range.

[Brief explanation of drawings]

Figure 1 is an explanatory diagram showing the cross-sectional shape of the angular structure. Figure 3 is a sectional view of a conventional windproof and vibration isolator, Figure 3 is a front view of a cable-stayed bridge showing the state in which the wind and vibration isolator of the present invention is installed.
Spear! The figure is a cross-sectional view of the main part, Fang 6 Hiro Fang! Reference explanatory diagrams shown to explain the device of the present invention shown in the figure. Figure 1 is a V-A curve diagram showing the wind tunnel test results of a square structure. V-A curve diagram corresponding to the structure, spear? The figure shows a V-A curve diagram corresponding to the angular structure in Figure 3, and a curve lθ.
The figure shows V-AE corresponding to the square structure of the present invention shown in Figure 3.
[fl! It is a diagram. (1)...Main tower, (/α)...Main tower surface in the airflow direction, (/A)...Main tower surface in the direction perpendicular to the airflow, (5)
...Driving plate.

Claims (2)

[Claims] (1) A flow guide plate with an arcuate cross-sectional shape is installed separately in the longitudinal direction of each corner of a square structure such as the main tower or girder of a suspension bridge or cable-stayed bridge, with the required ventilation channel gap. A windproof and vibration-proof device for a structure, characterized in that it prevents the occurrence of vortex-excited vibration and gear locking. (2) A windproof and vibration-proof device for a structure according to claim 1, characterized in that a flow guide plate is disposed in a range of about ⅓ or more of the length of the structure.